The present invention is directed to cooling assemblies and other apparatus used for removing heat from electronic devices. More particularly, the present invention is directed to an apparatus for cooling an electronic module through the utilization of thermoelectric cooling elements. Even more particularly, the present invention is directed to a geometric arrangement and configuration of thermoelectric module cooling elements in relation to heat transfer structures which may be placed in contact with an electronic device which is to be cooled.
It is well known that as the circuit density of electronic chip devices increases, there is a correspondingly increasing demand for the removal of heat generated by these devices. The increased heat demand has arisen both because the circuit devices are packed more closely together and because the circuits themselves are operated at increasingly high clock frequencies. Nonetheless, it is also known that runaway thermal conditions and excessive heat generated by chips is a leading cause for failure of chip devices. Furthermore, it is anticipated that the demand for heat removal for these devices will increase indefinitely. Accordingly, it is seen that there is a large and significant need to provide useful cooling mechanisms for electronic circuit devices.
The use of thermoelectric cooling elements is known. These elements operate electronically to produce a cooling effect. By passing a direct current through the legs of the thermoelectric module, a temperature difference is produced across the module which is contrary to that which would be expected from Fourier's Law.
At one junction of the thermoelectric element both holes and electrons move away, toward the other junction, as a consequence of the current flow through the junction. Holes move through the p-type material and electrons through the n-type material. To compensate for this loss of charge carriers, additional electrons are raised from the valence band to the conduction band to create new pairs of electrons and holes. Since energy is required to do this, heat is absorbed at this junction. Conversely, as an electron drops into a hole at the other junction, its surplus energy is released in the form of heat. This transfer of thermal energy from the cold junction to the hot junction is known as the Peltier effect.
This permits the surfaces attached to a heat source to be maintained at a temperature below that of a surface attached to a heat sink. What these thermoelectric modules provide is the ability to operate the cold side below the ambient temperature of the cooling medium (air or water) or provide greater heat removal capacity for a given cold plate or component temperature. When direct current is passed through these thermoelectric modules a temperature difference is produced with the result that one side is relatively cooler than the other side. These thermoelectric modules are therefore seen to possess a hot side and a cold side. These devices provide a mechanism for facilitating the transfer of thermal energy from the cold side of the thermoelectric module to the hot side of the module.
However, conventional configurations of these devices are nonetheless seen to be unnecessarily limiting in terms of the thermal energy which may be transferred. Thus while the use of thermoelectric modules is seen to provide a means for the solid state cooling of adjacent electrical devices, their efficiency has been less than optimal.